In these years, a large amount of paper as recording material on which images are to be formed has been consumed because electrophotographic image forming apparatuses such as copiers, printers, and facsimile machines have become widely used. Here, paper used as recording material is made from wood pulp as a raw material. Therefore, in terms of the global environment, it has been an important social issue to protect forests by reducing paper consumption and preventing a decrease in forests due to logging.
Further, since paper includes incombustible or non-decomposable inorganic components, wasted materials that require the use of landfills are generated at a certain ratio when paper is discarded. In these years, however, it has become difficult to newly reserve landfills, so that also in terms of waste reduction, it remains a social issue to reduce paper consumption.
Therefore, conventionally, in order to deal with these issues, paper once used is collected instead of being discarded as trash, and the collected wastepaper is first defibrated into pulp in a paper mill and is reused as recycled paper. There are many problems, however, in the process of collecting wastepaper and turning it into recycled paper, such as the possibility of leakage of corporate classified papers or data at the time of collecting wastepaper, time and effort for sorting wastepaper by paper type, and degradation of the pulp quality of re-pulped wastepaper.
Therefore, in order to solve these problems, techniques have been proposed in these years that enable recording material to be reusable by peeling off and removing an image on the recording material. (See, for example, Patent Documents 1, 2, 3, and 4 listed below.)
Patent Document 1 describes the technique of peeling off and removing a thermoflexible image forming substance of an image formed on paper by electrophotography by impregnating the paper with a liquid including water to reduce the adhesion between the paper and the image forming substance and causing the paper and a peeling roller serving as a peeling member to come into heated press contact.
Patent Document 2 describes an apparatus for removing an image formed on recording material by transferring and peeling off the image by using an endless peeling belt having a hot-melt resin layer at its surface and applying heat and pressure to the recording material placed on top of the surface of the peeling belt.
Patent Documents 3 and 4 each describe an image remover that uses a roller-shaped peeling member that includes a silicone rubber layer provided on the surface of a metal core bar and a thermoplastic resin layer provided on this silicone rubber layer.
[Patent Document 1] Japanese Laid-Open Patent Application No. 7-13383
[Patent Document 2] Japanese Patent No. 2584112 (Japanese Laid-Open Patent Application No. 4-64472)
[Patent Document 3] Japanese Laid-Open Patent Application No. 2002-72792
[Patent Document 4] Japanese Laid-Open Patent Application No. 2001-66957
Patent Document 1 uses a rubber roller as a peeling roller, and the rubber roller is formed of a material commonly used as rubber, such as natural rubber, chloroprene rubber, isoprene rubber, styrene-isoprene rubber, or silicone rubber. However, these rubber materials are low in adhesion to toner, which is a thermoplastic image forming substance, so that the image on the recording material cannot be completely removed. Further, in the case of applying an image removal accelerating liquid including water to the recording material, the image may be removed to some extent with the rubber roller because the adhesion between the image and the paper is reduced. However, it is difficult to remove a low-density gradation image.
Further, there is a problem in that even when reusable recording material is formed by adding a composition that reduces adhesion to an image forming substance to the recording material to be used, and an attempt is made to remove an image formed on the reusable recording material by thermal transfer, which does not employ an image removal accelerating liquid, the image on the recording material can hardly be removed if the recording material is formed so as to present an image fixing characteristic sufficient for practical use, because the adhesion of the image forming substance to the rubber material becomes lower than the adhesion of the image forming substance to the recording material.
Further, if metal or a plastic film without a thermoplastic resin surface layer is employed as a peeling member, it is difficult to remove an image forming substance in concave parts at a paper surface. In particular, it is difficult to completely remove image forming substance particles that form background fogging and adhere alone or a low-density image. In particular, unlike a monochrome image, a color image also includes a secondary color and a tertiary color. Therefore, the height of the image is stepped. If there is a “high” image of a secondary color around a “low” image such as a monochromatic gradation image, it is difficult for the peeling member to come into contact with the “low” image. This causes the image forming substance to remain in the stepped image.
In general, in color images, heat fusing is performed until the surface of the image forming substance becomes continuously flat on the surface of the recording material in order to increase chroma. Therefore, even when an image removal accelerating liquid is applied from the surface of the image, the image removal accelerating liquid is blocked by the image forming substance and is prevented from reaching the cellulose fibers of the paper, thus making it difficult to remove the image.
Further, according to Patent Document 1, the image removal accelerating liquid including water is applied to the recording material. However, even if the amount of the liquid applied is only a little, repeated use of the recording material causes problems such as generation of wrinkles or curl and occurrence of a conveyance jam due to the generation of curl at the time of processing in an image forming apparatus or image remover. Thus, the number of times the recording material can be repeatedly used cannot be increased. Further, adding a large amount of the liquid causes problems such as the need for a large amount of energy to dry the absorbed liquid and a change in the size of the recycled recording material.
According to Patent Document 2, a thermoplastic or heat-melt resin layer is provided on the surface of a peeling member, and the surface of the peeling member and recording material are placed on top of each other to be subjected to heating and pressing. As a result, the surface of the peeling member deforms in accordance with the unevenness of an image on the recording material, so that the peeling member and the image are in good contact, thus improving the image removal characteristic. However, it is difficult to completely remove the image even with a peeling member (peeling belt) where a heat-melt resin is provided on an endless belt of metal or a heat-resistant organic polymer material such as a polyimide film. In particular, in the case of forming a color image including a secondary color and a tertiary color on the recording material, multiple layers of the image forming substance are formed, and it is difficult to remove a “low” low-density image around a multi-layer “high” image or the image forming substance that has been scattered around the image at the time of the transfer of the image to the recording material.
Further, there are also problems in the case of using an endless belt (peeling belt) as a peeling member. For example, if the peeling belt deviates to one side because of its continuous use, it is difficult to correct the deviation. If the deviation is forcibly corrected, an uneven tension is exerted on the peeling belt in its widthwise directions, so as to cause deformation of the peeling belt and reduction of its useful service life. In particular, if a cleaning part is provided for removing the image forming substance transferred from the recording material onto the peeling belt, at least two nips, one for transferring the image forming substance of the recording material onto the peeling belt and the other between the cleaning part and the peeing belt, are formed. This makes it extremely difficult to solve the problem of the deviation of the peeling belt.
A peeling member having such a configuration as described in Patent Document 3 or Patent Document 4 has the problem of low adhesion between the rubber layer and the thermoplastic layer. Therefore, there is a problem in that if recording material having an adhesion (fixing) characteristic sufficient for practical use with respect to the image forming substance is used, the image forming substance on the recording material cannot be completely removed or the thermoplastic layer on the recording material is peeled off from the rubber layer so as to be transferred in reverse onto the recording material.
Further, there is a problem in the case of using recording material having low adhesion to the image forming substance. In this case, the image forming substance on the recording material can be removed at first. However, since the molecules of the rubber-like composition can move relatively freely as a characteristic of the rubber-like composition, a component of the thermoplastic resin layer provided on the rubber elasticity layer or a component of the image forming substance transferred onto the thermoplastic resin layer is mixed into the rubber elasticity layer, so that continuous use causes the rubber elasticity layer to swell and deform or makes it impossible to remove the image forming substance from the recording material.